1. Field of the Invention
The present invention relates to a network in which a plurality of electronic apparatuses are connected by a bus, such as a high-speed serial bus conforming to IEEE1394 (hereinafter referred to as an IEEE1394 bus) and communications are performed among the electronic apparatuses. More particularly, the present invention relates to an apparatus and method for solving the problem of incompatibility of transmission data formats, which may occur between a transmission-side apparatus and a receiving-side apparatus when data is transmitted.
2. Description of the Related Art
A network has been conceived in which electronic apparatuses (hereinafter referred to as apparatuses), such as digital video cassette recorders, digital still cameras, personal computers, and printers, are connected through an IEEE1394 bus, and communications are performed among these apparatuses.
In a network in which a plurality of such apparatuses are connected by an IEEE1394 bus (hereinafter referred to as an IEEE1394 network), transmission of data and control signals is performed by time division multiplexing at a predetermined communication cycle. As communication configurations in one communication cycle, there are isochronous (hereinafter referred to as Iso) communication in which video data, audio data, and the like are transmitted in real time, and asynchronous (hereinafter referred to as Async) communication in which a control signal, such as an operation control command and a connection control command of an apparatus, is transmitted at non-fixed intervals as required.
When a print data supply apparatus on an IEEE1394 network transmits print data to a printer apparatus and instructs printing, it is necessary for the print data supply apparatus to provide and transmit data conforming to a data format which can be received and printed by a printer apparatus.
The print data supply apparatus must change the format of print data to be transmitted depending upon the printer apparatus of a print data transmission destination. In a case where a plurality of print data supply apparatuses are connected on the network, all of these apparatuses need to have a print data format conversion function, with the result that the same function is present at a plurality of places on the network and the resources are wasted.
Also, when the print data supply apparatus cannot transmit data conforming to a data format which can be received and printed by the printer apparatus, the problem that the printer apparatus cannot print specified data occurs.
An object of the present invention, which has been achieved in view of such situations, is to provide an apparatus and method for converting the format of data to be transmitted into an appropriate form and transmitting the data to a receiving apparatus in a case where a data transmission apparatus and the data receiving apparatus are connected on an IEEE1394 network and the data receiving apparatus is not designed to support the data format which can be output by the data transmission apparatus.
According to a first aspect, the present invention which achieves this object relates to an electronic apparatus on a communication network comprising a bus and a plurality of electronic apparatuses connected to the bus, the electronic apparatus comprising: means for checking functions implemented by at least a first electronic apparatus and a second electronic apparatus on the network; first determination means for determining whether a data format which can be transmitted by the first electronic apparatus can be received by the second electronic apparatus on the basis of the functions implemented by the first electronic apparatus and the second electronic apparatus; and control means for performing control so that data is transmitted from the first electronic apparatus to the second electronic apparatus when it is determined by the first determination means that the data format which can be transmitted by the first electronic apparatus can be received by the second electronic apparatus.
According to a second aspect, the present invention which achieves this object relates to an electronic apparatus further comprising: holding means for holding information of a convertible data format; second determination means for determining whether a data format which can be transmitted the first electronic apparatus can be converted into a format which can be received by the second electronic apparatus on the basis of the information of the data format; and data format conversion means for converting the data format which can be transmitted by the first electronic apparatus into a format which can be received by the second electronic apparatus when the first determination means determines that the data format which can be transmitted by the first electronic apparatus can be received by the second electronic apparatus and the second determination means determines that the data format which can be transmitted by the first electronic apparatus can be received by the second electronic apparatus.
According to a third aspect, the present invention which achieves this object relates to an electronic apparatus further comprising: acquisition means for acquiring information of a convertible data format in another electronic apparatus from among the plurality of electronic apparatuses; third determination means for determining whether the other electronic apparatus can convert the data format which can be transmitted by the first electronic apparatus into a format which can be received by the second electronic apparatus on the basis of the information of the convertible data format in the other electronic apparatus; and control means for controlling the other electronic apparatus so as to convert the data format which can be transmitted by the first electronic apparatus into a format which can be received by the second electronic apparatus when the first determination means determines that the data format which can be transmitted by the first electronic apparatus cannot be received by the second electronic apparatus, the second determination means determines that the data format which can be transmitted by the first electronic apparatus cannot be converted into a format which can be received by the second electronic apparatus, and the third determination means determines that the data format which can be transmitted by the first electronic apparatus can be converted into a format which can be received by the second electronic apparatus.
According to a fourth aspect, the present invention which achieves this object relates to an electronic apparatus on a communication network comprising a bus and a plurality of electronic apparatuses connected to the bus, the electronic apparatus comprising: holding means for holding information of a convertible data format; first input means for inputting control data from another electronic apparatus from among the plurality of electronic apparatuses; second input means for inputting data transmitted over the bus from the first electronic apparatus; data format conversion means for converting the data from a first data format into a second data format on the basis of the control data; and data output means for outputting the data which has been converted into the second data format.
According to a fifth aspect, the present invention which achieves this object relates to a data communication method on a communication network comprising a bus and a plurality of electronic apparatuses connected to the bus, the data communication method comprising: a step for acquiring information of a data format which can be transmitted by a source apparatus which provides data from among the plurality of apparatuses; a step for acquiring information of a data format which can be received by a destination apparatus which receives data from among the plurality of electronic apparatuses; and a step for determining whether the data format which can be transmitted by the source apparatus can be received by the destination apparatus on the basis of the information of the transmittable data format and information of the receivable data format.
According to a sixth aspect, the present invention which achieves this object relates to a data communication method further comprising: a control step for performing control so that data is transmitted from the source apparatus to the destination apparatus when the data format which can be transmitted by the source apparatus can be received by the destination apparatus.
According to a seventh aspect, the present invention which achieves this object relates to a data communication method further comprising: a step for referencing information of a convertible data format when the data format which can be transmitted by the source apparatus cannot be received by the destination apparatus; a step for determining whether the data format which can be transmitted by the source apparatus can be converted into a data format which can be received by the destination apparatus on the basis of the information of the transmittable data format and the information of the convertible data format; and a step for performing control so that when it is determined in the determination step that the data format which can be transmitted by the source apparatus can be received by the destination apparatus, the data format which can be transmitted by the source apparatus is converted into a format which can be received by the destination apparatus.
According to an eighth aspect, the present invention which achieves this object relates to a data communication method on a communication network comprising a bus and a plurality of electronic apparatuses connected to the bus, the data communication method comprising: a step for inputting control data from another electronic apparatus from among the plurality of electronic apparatuses; a data input step for inputting data transmitted over the bus from a first electronic apparatus; a data format conversion step for converting the data from a first data format into a second data format on the basis of the control data; and a data output step for outputting the data which has been converted into the second data format over the bus.
In the present invention, at a predetermined point in time, an apparatus for transmitting data on the network is defined as a source apparatus, and an apparatus for receiving and processing data is defined as a destination apparatus. Further, an apparatus for instructing and controlling an apparatus connected on the network so as to transmit data is defined as a controller, and a data format conversion function is implemented in the controller.
The transmission of data from the source apparatus to the destination apparatus is instructed by the controller. The source apparatus has, as apparatus information, a list of data formats which can be transmitted, and the destination apparatus has, as apparatus information, a list of data formats which can be received and processed.
When instructing transmission of data from the source apparatus to the destination apparatus, the controller acquires information of a data format which can be transmitted by the source apparatus and information of a data format which can be received by the destination apparatus, determines, from the information, a data format suitable for the transmission, and instructs the source apparatus to transmit data in the specified format to a destination.
When an appropriate format cannot be found, the controller determines a data format which can be transmitted by the source apparatus and a data format which can be received by the destination apparatus by referring also to data format information which can be converted by the controller itself, and instructs the source apparatus to transmit data in that data format to the controller. The controller receiving the data converts the data format into a format which can be received by the destination apparatus and transmits the data to the destination apparatus.
The above and further objects, aspects and novel features of the invention will become more apparent from the following detailed description when read in connection with the accompanying drawings.